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在60950的4.7.2.2 Parts not requiring a fire enclosure中有写) I) _- e9 @5 Z/ Q2 s$ u/ u
components in SECONDARY CIRCUITS:supplied by internal or external power sources that are limited to a maximum of 15 VA! w. k) t( ^9 a2 h) _, `0 i ?6 [
(see 1.4.11) under normal operating conditions and after a single fault in the equipment1 t3 g* B& z" w6 A7 B
(see 1.4.14) and mounted on HB75 CLASS MATERIA,L if the thinnest significant thickness ~ g+ s1 x$ N; {; m5 V: n$ f, {
of this material is < 3 mm, or HB40 CLASS MATERIAL, if the thinnest significant thickness of
" E9 t6 ~* t% @0 bthis material is ≥ 3 mm;
: {: m9 {/ j ?1 F这里说如果PCB板的厚度<3mm,它至少要用HB75 CLASS MATERIA,如果PCB板的厚度>3mm,它至少要用HB40CLASS MATERIA,75的等级不是比40的要低吗?板子越薄应该用较高的防火等级才是啊,怎么是相反的呢?
, w# x6 }. p( o1 b/ G) K( }哪位高手能指点迷津啊?非常感谢。 |
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